Being comparable with liquid crystal displays (LCD), a typical flat panel displays such as plasma display panel (PDP) has good developing perspective. In PDPs, the key material is an efficient phosphor, and the key techniques to realize its industrial production are how to produce this efficient phosphor particles, how to enlarge the emitting area of luminescence particles and how to improve the brightness, color purity, definition and color displaying quality.
Europium activated yttrium gadolinium borate phosphor particles can be used in PDPs. In the prior art, these phosphors are prepared by a high temperature solid state reaction. This method has many technical disadvantages. For example, this method consumes much energy during preparation, and the coarser grain size of phosphor powders prepared by this method is in the range of 5 to 10 microns and the particle size distribution is not uniform, making the quality of coating screen low. The above method is prone to forming a non-uniformity of dispersion, whereby influencing the emitting efficiency.
WO99/38186 of Panasonic Electronic Co. (Japan) discloses an improved method for the production of europium activated yttrium gadolinium borate phosphors, this publication is incorporated herein by reference entirely. In this method, fine grain size of phosphor particles were synthesized by sol-gel process. This method comprises the formation of a sol and/or gel by the reaction of, in an acidic solution, organic precursors containing yttrium, gadolinium, alkaline earth metals, europium and boron; and thermally decomposing the gel at a temperature lower than the temperature of the solid phase reaction. By contrast with the high temperature solid state reaction, this method has the advantages of improving the particles shape and uniformity and decreasing the particle size. However, this method still has the disadvantages of longer preparation period (5-6 days), and coarser particle sizes (0.1-2.0 micron), which are not fine enough.
The main object of the present invention is to overcome the above-mentioned shortcomings and to provide a method for producing europium activated yttrium gadolinium borate phosphor particles with the advantages of shortening the production period, increasing the production efficiency, further decreasing the particle size and improving the product uniformity. With fine particles in production of PDP screens, it is easy to form thin fluorescence screens, increase the specific surface of phosphor particles and improve the emitting performance.